springbatch

• job：作业，是批处理中的核心概念，是batch操作的基础单元，每个job由多个step组成

• step：步骤，任务完成的节点

• 每个job是由JobBuildFactory创建，每个step是由StepBuildFactory创建

• 示例：

  ``

  @Configuration

  @EnableBatchProcessing //开启批处理

  public class JobConfiguration {

      /**
       * 创建任务对象的对象
       */
      @Autowired
      private JobBuilderFactory jobBuilderFactory;
  /**
   * 创建步骤对象的对象
   */
  @Autowired
  private StepBuilderFactory stepBuilderFactory;
  
  @Bean
  public Job helloJob(){
  
      return jobBuilderFactory.get("helloJob").start(helloStep1()).build();
  }
  
  @Bean
  public Step helloStep1(){
  
      return stepBuilderFactory.get("helloStep1").tasklet(new Tasklet() {
          @Override
          public RepeatStatus execute(StepContribution stepContribution, ChunkContext chunkContext) throws Exception {
              System.out.println("hello world");
              return RepeatStatus.FINISHED;
          }
      }).build();
  }
  }

  ``

• JdbcPagingItemReader

    . 设置数据源
    . 设置查询条件
    . 将查询结果映射成实体类

• MySqlPagingQueryProvider // mysql分页查询支持器

• 代码示例：

      JdbcPagingItemReader<User> jdbcPagingItemReader = new JdbcPagingItemReader<>();
      jdbcPagingItemReader.setDataSource(dataSource);
      jdbcPagingItemReader.setFetchSize(3);//每次从数据库拉取条数
  //设置查询条件
  MySqlPagingQueryProvider pagingQueryProvider = new MySqlPagingQueryProvider();
  pagingQueryProvider.setSelectClause("id,name,password");
  pagingQueryProvider.setFromClause("user");
  
  Map&lt;String, Order&gt; orderMap = new HashMap&lt;&gt;();
  orderMap.put("password",Order.DESCENDING);//设置排序字段
  pagingQueryProvider.setSortKeys(orderMap);
  jdbcPagingItemReader.setQueryProvider(pagingQueryProvider);
  
  //设置行映射器
  jdbcPagingItemReader.setRowMapper(new RowMapper&lt;User&gt;() {
      @Override
      public User mapRow(ResultSet resultSet, int i) throws SQLException {
          User user = new User();
          user.setId(resultSet.getInt(1));
          user.setName(resultSet.getString(2));
          user.setPassword(resultSet.getString(3));
          return user;
      }
  });
  return jdbcPagingItemReader;</code></pre></li>
  FlatFileItemReader
  DelimitedLineTokenizer //行分词器
  DefaultLineMapper //行映射器，将一行数据映射成对应的实体
  defaultLineMapper.setLineTokenizer(delimitedLineTokenizer);
  flatFileItemReader.setLineMapper(defaultLineMapper);
  代码示例：
      FlatFileItemReader<Hospital> flatFileItemReader = new FlatFileItemReader<>();
      flatFileItemReader.setEncoding("utf-8");
      flatFileItemReader.setLinesToSkip(1);//跳过第一行
      flatFileItemReader.setResource(new ClassPathResource("/data/hospital.txt"));
  //解析数据  按行分词
  DelimitedLineTokenizer delimitedLineTokenizer = new DelimitedLineTokenizer();
  delimitedLineTokenizer.setNames("id","org_name","org_type","addr","allow_no","cert_dept",
          "start_valid_date","end_invalid_date");
  
  //行映射器
  DefaultLineMapper&lt;Hospital&gt; defaultLineMapper = new DefaultLineMapper&lt;&gt;();
  defaultLineMapper.setLineTokenizer(delimitedLineTokenizer);
  defaultLineMapper.setFieldSetMapper(new FieldSetMapper&lt;Hospital&gt;() {
      @Override
      public Hospital mapFieldSet(FieldSet fieldSet) throws BindException {
          Hospital hospital = new Hospital();
          hospital.setId(fieldSet.readInt("id"));
          hospital.setAddr(fieldSet.readString("addr"));
          hospital.setAllowNo(fieldSet.readString("allow_no"));
          hospital.setCertDept(fieldSet.readString("cert_dept"));
          hospital.setEndValidDate(fieldSet.readString("end_invalid_date"));
          hospital.setOrgName(fieldSet.readString("org_name"));
          hospital.setOrgType(fieldSet.readString("org_type"));
          hospital.setStartValidDate(fieldSet.readString("start_valid_date"));
          return hospital;
      }
  });
  defaultLineMapper.afterPropertiesSet();
  flatFileItemReader.setLineMapper(defaultLineMapper);
  
  return flatFileItemReader;</code></pre></li>
  StaxEventItemReader xml读取器
  pom引入jar包
  ``
    <dependency>
        <groupId>com.thoughtworks.xstream</groupId>
        <artifactId>xstream</artifactId>
        <version>1.4.11.1</version>
    </dependency>
  
    <dependency>
        <groupId>org.springframework</groupId>
        <artifactId>spring-oxm</artifactId>
        <version>5.0.8.RELEASE</version>
    </dependency>
  ``
  xstream实现xml转对象
  spring-oxm遵循xstream接口规范，实现xml转对象
  代码示例：
  ``
        @Bean
        public ItemReader<User> xmlItemReader() {
        StaxEventItemReader&lt;User&gt; staxEventItemReader = new StaxEventItemReader&lt;&gt;();
        staxEventItemReader.setFragmentRootElementName("user");//设置根标签
        staxEventItemReader.setResource(new ClassPathResource("/data/user.xml"));//设置文件路径
  
        //将xml转成实体对象
        XStreamMarshaller xStreamMarshaller = new XStreamMarshaller();
        Map&lt;String,Class&gt; alias = new HashMap&lt;&gt;();
        alias.put("user",User.class);//key 为根标签，class是key标签下的所有标签映射到的对象
        xStreamMarshaller.setAliases(alias);
  
        staxEventItemReader.setUnmarshaller(xStreamMarshaller);
  
        return staxEventItemReader;
    }</code></pre>
  ``
  
  MultiResourceItemReader
  多文件读取，其实就是一个一个文件读取
  MultiResourceItemReader需要设置文件读取代理，待读取文件资源
  代码示例：
  ``
  @Value("classpath:/data/file*.txt")  
  private Resource[] resources;
  @Bean  
  public MultiResourceItemReader multiFileItemReader() {
     MultiResourceItemReader<Hospital> multiResourceItemReader = new MultiResourceItemReader<>();
     //多文件读取，其实也是一个一个文件进行读取，需要设置文件读取器
     multiResourceItemReader.setDelegate(flatFileItemReader());
     multiResourceItemReader.setResources(resources);
     return multiResourceItemReader;
  }
  @Bean  
  public FlatFileItemReader flatFileItemReader(){  
  FlatFileItemReader flatFileItemReader = new FlatFileItemReader<>();  
  flatFileItemReader.setEncoding("utf-8");
     DelimitedLineTokenizer delimitedLineTokenizer = new DelimitedLineTokenizer();
     delimitedLineTokenizer.setDelimiter(",");
     delimitedLineTokenizer.setNames("id","org_name","org_type","addr","allow_no","cert_dept",
             "start_valid_date","end_invalid_date");
  
     DefaultLineMapper<Hospital> defaultLineMapper = new DefaultLineMapper<>();
     defaultLineMapper.setLineTokenizer(delimitedLineTokenizer);
     defaultLineMapper.setFieldSetMapper(new FieldSetMapper<Hospital>() {
         @Override
         public Hospital mapFieldSet(FieldSet fieldSet) throws BindException {
             Hospital hospital = new Hospital();
             hospital.setStartValidDate(fieldSet.readString("start_valid_date"));
             hospital.setOrgType(fieldSet.readString("org_type"));
             hospital.setOrgName(fieldSet.readString("org_name"));
             hospital.setEndValidDate(fieldSet.readString("end_invalid_date"));
             hospital.setCertDept(fieldSet.readString("cert_dept"));
             hospital.setAllowNo(fieldSet.readString("allow_no"));
             hospital.setAddr(fieldSet.readString("addr"));
             hospital.setId(fieldSet.readInt("id"));
             return hospital;
         }
     });
  
     flatFileItemReader.setLineMapper(defaultLineMapper);
  
     return flatFileItemReader;
  }  
  ``
  JdbcBatchItemWriter
  代码示例：
      @Bean
      public ItemWriter<Hospital> jdbcBatchItemWriter() {
          JdbcBatchItemWriter<Hospital> jdbcBatchItemWriter = new JdbcBatchItemWriter<>();
          jdbcBatchItemWriter.setDataSource(dataSource);
          jdbcBatchItemWriter.setSql(
                  "INSERT INTO `hospital` (`id`, `org_name`, `org_type`, `addr`, `allow_no`, `cert_dept`, `start_valid_date`, `end_invalid_date`) " +
                          "VALUES (:id, :orgName, :orgType, :addr, :allowNo, :certDept, :startValidDate, :endValidDate)"
          );
          //将对象属性值映射到sql参数中
          jdbcBatchItemWriter.setItemSqlParameterSourceProvider(new BeanPropertyItemSqlParameterSourceProvider<>());
          return jdbcBatchItemWriter;
      }
  
  
  FlatItemFileWriter
  代码示例：
      @Bean
      public ItemWriter<? super Hospital> flatFileItemWriter() {
      FlatFileItemWriter&lt;Hospital&gt; flatFileItemWriter = new FlatFileItemWriter&lt;&gt;();
      flatFileItemWriter.setEncoding("utf-8");
      //设置存放数据的文件路径
      flatFileItemWriter.setResource(new FileSystemResource("f:/hospital_generate.txt"));
  
      flatFileItemWriter.setLineAggregator(new LineAggregator&lt;Hospital&gt;() {
          ObjectMapper objectMapper = new ObjectMapper();
          @Override
          public String aggregate(Hospital item) {
              String result = null;
              try {
                  result = objectMapper.writeValueAsString(item);//将对象转json字符串
              } catch (JsonProcessingException e) {
                  e.printStackTrace();
              }
  
              return result;
          }
      });
      return flatFileItemWriter;
  
  }</code></pre></li>
  StaxEventItemWriter
  XstreamMarshaller - xml标签元素与实体对象映射
  代码示例
      @Bean
      public ItemWriter<? super Hospital> xmlFileItemWriter() {
          StaxEventItemWriter<Hospital> staxEventItemWriter = new StaxEventItemWriter<>();
          staxEventItemWriter.setEncoding("utf-8");
          staxEventItemWriter.setResource(new FileSystemResource("f:/hospital.xml"));
          staxEventItemWriter.setRootTagName("hospitals");
      //XML标签与实体对象映射
      Map&lt;String,Class&lt;Hospital&gt;&gt; alias = new HashMap&lt;&gt;();
      alias.put("hospital",Hospital.class);
  
      XStreamMarshaller xStreamMarshaller = new XStreamMarshaller();
      xStreamMarshaller.setAliases(alias);
  
      staxEventItemWriter.setMarshaller(xStreamMarshaller);
  
      return staxEventItemWriter;
  
  }</code></pre></li>